The stators and rotors of turbine-alternator groups like those found in hydroelectric dams can become soaked with oil and carbon. A clogged stator is synonymous of a temperature increase, which in certain cases, causes production limitations. Moreover, when the alternator is very dirty, there is a degradation of the insulating paints, thereby reducing the useful life of the winding.
A cleaning is highly desirable to ensure the reliability of the equipment, to prevent the degradation of the windings, to extend the lifetime of the alternator, to influence the rate of forced stops and the rate of unavailability of the groups, and to reduce the temperature of the stator windings (by the cleaning of the ventilation channels, the temperature drop causing a reduction of the copper losses at the rotor and the stator).
However, hitherto, the rotor must be removed from the alternator to then proceed with the cleaning of the stator using classical methods (e.g. manual cleaning using cloths and brushes), operation which is expensive, more or less safe and which causes a 12- to 16-week forced stop of the turbine-alternator group subjected to the cleaning. Because of this, the cleaning operations are often deferred due to the lengthy period of the unavailability of the turbine-alternator groups.